Stomiiformes: Phosichthyidae 885

PHOSICHTHYIDAE Lightfishes (lighthousefishes) by A.S. Harold, Grice Marine Biological Laboratory, South Carolina, USA iagnostic characters: Maximum size about 30 cm. Body generally moderately elongate, somewhat Ddeep-bodied in some Ichthyococcus species, head small to moderately large. Head and body com- pressed. Mouth large; teeth ranging in size from small to large but not highly elongate and fang-like. Chin barbel absent. Eleven to 22 branchiostegal rays, 4 to 7 on posterior ceratohyal. Gill rakers well developed (but true gill rakers restricted to angle of arch in Woodsia). Pseudobranchiae absent, except Woodsia meyerwaardeni. Dorsal fin usually near middle of body, its origin well in advance of that of anal fin (ex- cept Pollichthys which has dorsal-fin orgin immediately above that of anal fin). Dorsal adipose fin pres- ent (except Yarrella). Anal fin with moderately long base but terminating posteriorly ahead of most constricted portion of caudal peduncle. Dorsal fin with 10 to 16 rays; anal fin with 12 to 33 soft rays; caudal fin forked; pectoral-fin soft rays 7 to 11; pelvic-fin soft rays 6 to 8. Scales present, deciduous. Two ventrolateral rows of well-developed photophores on body, rows of accessory photophores dorsal to main rows in Yarrella; OA 17 to 53; IV 19 to 28; VAV 7 to 17; AC 12 to 28; paired row of photophores on isthmus (IP); 2 orbital photophores, except Polymetme and Yarrella which lack the posterior (ORB 2).Three pec- toral-fin radials. Usually 2 supramaxillae. Colour: skin varying from light brown in Pollichthys to dark brown or nearly black in Yarrella.

OP ORB OA adipose fin

SO IV AC lateral view VAV PV

BR OA AC

PV VAV ventral view IP

IV

AC - ventral series posterior to anal-fin origin OP - opercular photophores BR - on the branchiostegal membranes ORB - anterior (ORB1) and posterior (ORB2) to eye IP - ventral series anterior to pectoral-fin base PV - ventral series between bases of pectoral and pelvic fins IV - ventral series anterior to pelvic-fin base SO - paired photophores near symphysis of lower jaw OA - lateral series VAV - ventral series between pelvic-fin base and anal-fin origin

abbreviated terminology of photophores